Thinking on it, this could apply to a couple things.
If it's in the context of a zone having a sequel as a zone, there's really one zone on the rumored line-up that would fit and that's the Mardi Gras zone. We've had Zombie Gras in 2010, so we could have a sequel to that...if it's Mardi Gras, that is.
If the zone turns out to be more of an opulent Masquerade, well we had Blood Masquerade in 2006, so that could possibly have a sequel. We know the event does love their vamps, though you could have some other monsters join the soiree in disguise.
But if it's in the context of a house being a sequel to a zone, there's two firm options.
The rumored Viking house: Back in 2019 we had Vikings Undead, so a viking house could very well be a sequel to that.
The rumored Graveyard house: I mean, dual scythes have been in the rumored symbol for quite a while, we had Death and Sleep in 2022's excellent Graveyard zone, there's Jeffery Gooner talking about how the house is akin to Graveyard Games and the Graveyard zone...quack quack quack.